Pickup arm control



met so, 1945. A L KNOX E TAL 2,387,916

PICKUP ARM CONTROL Original Filed Deo, 3l, 1940 2 Sheets sheet 1iNvz-:NToRs ARTHUR Knox FRI Y. HL

Oct. 30, 1945.

A. L. KNOXl ETAL PICKUP ARM CONTROL original Filed Dec.- s1, 1940 2Shets-Sheet 2 28 FIG. 2

INVENTORS ARTHUR L. K NOX Patented Oct. 30, 1945 PICKUP ARM CONTROLArthur L. Knox and Fritz Kahl, Fort Wayne, Ind., assignors to FarnsworthTelevision and Radio Corporation, a corporation of Delaware Originalapplication December 31, 1940, Serial No. 372,681. Divided and thisapplication May 1, 1943, Serial No. 485,266

8 Claims.

an improved mechanism for controlling the movement of the pickup armused with record-changing apparatus.

' In accordance with the present invention, there is provided for use inan automatic record-changing apparatus a turntable, a pickup arm forcooperating with a record on the turntable and a cam means for movingthe pickup arm. IA swinging means, which is associated with the pickuparm and the cam means, imparts to the pickup arm a relatively fastoutward movement and a relatively slow inward movement.

In accordance with a further feature of the present invention', there isprovided for use in an automatic record-changing apparatus a turntable,a pickup arm for cooperating with a record on the turntable, and a cammeans for moving the pickup arm. yA first means is associated with thecam means and the pickup arm for imparting a raising and loweringmovement to the kpickup arm. A second means is associated with the cammeans and the pickup arm for imparting to the pickup arm an outward andan inward movement. A spring means is associated with the second meansfor moving a stylus of the pickup arm into the outer groove of a recordon the turntable after the stylus of the pickup arm is brought intoengagement with a record on the turntable.

For a better understanding of the invention, together with other andfurther objects thereof, reference is made to the following descriptiontaken in connection with the accompanying drawings, and its steps willbe pointed out in the appended claims.

In the accompanying drawings:

Fig. l is a. fragmentary side elevation view partly in section of thepickup arm support, land the mechanism for elevating the pickup arm;l

Fig. 2 is a fragmentary side elevation view showing the mechanism formoving 'the pickup arm horizontally; f

Fig. 3 is a.l perspective View of the pickup armcam wheel, showing thecontour of the cam surface for controlling the horizontal movement ofthe pickup arm;

Figs. 4, 5 and 6 are fragm line 4-4 of Fig. 2, show-ingvarlous positionsof the members for controlling the horizontal movement of the pickup armWhen'the stylus of the pickup arm is at the beginning of a record, whenthe stylus moves into the trip groove at the end oi a record and whenthe pickup arm has been moved to its outwardmost position; and

Fig.' 7 is a fragmentary view taken on line 1--1 of Fig. 2 showing themechanism for controlling the inward movement of the pickup arm toposition the stylus over the initial playing groove of a twelve-inchrecord.

Referring now particularly to Fig. 1 of the drawings, the invention hereillustrated shows a record-playing apparatus which includes a base plateI0. Disposed above the base plate I0 is a horizontally rotatableturntable I I for supporting a record I2 to be played. The turntable IImay 'tary views taken on be rotated by a mechanism shown and fullydescribed in theA above-mentioned application.

Means for playing the record I2 comprises a reproducer I3 with a stylusI4 (Fig. 1) which cooperates with the record on the turntable I I. The

reproducer I3 is supported at the free end of av pickup arm I5, theother end of which is pivotally mounted on a pedestal I6 to permit thereproducer I3 and the pickup arm I5 to move 'in a horizontal andvertical plane.

When the stylus of the pickup arm I5 reaches the inner groove of arecord, the pickup arm is elevated and then swung outwardly in ahorlzontal plane to a position where it will not interfere with arecord-changing cycle.

The means for elevating the pickup arm includes a cam wheel I8 (Figs. 1and 2) fixed to the shaft I9. The cam I8' and shaft I9 may be driven bya mechanism disclosed in ourv copending application. The cam wheel I8has a cam surface 2I with a notched portion 22. A roller 23, which isfixed to one end of a lever 24, is adapted to engage the cam surface 2I.The other 'end of the lever 24 is connected to a bracket 25 which issuspended from the base plate IIJ (Fig. l) so that the lever 24may-pivot in a vertical plane. An adjustable screw 26 is supported bythe lever 24 intermediate its ends. The screw 26 supports a. rod 21which extends upwardly ina hollow shaft 28. The shaft 28 'is rotatablewithin the pedestal I6 and is adapted to be moved vertically therein.The shaft y28 has-an irregularshaped plate 30 fixed to the top thereof..The platel 30 is adapted to move freely over' the top of the pedestalI6. One end of the plate 30 is vided a bearing 85 which pivotailysupports a bracket 36 by means of a pin Si. The pickup arm iii isaffixed to the bracket 36 so as to pivot on the bearing pin 'Jl when thestylus ci the reproducer i3 is in engagement with a record on theturntable. .Pl suitable weight is provided in the pivoted end of thepickup arm i5 as shown in Fig. l to maintain a predetermined styluspressure on the record on the turntable. An adjustable screw dil isprovided on the lefthand end of the plate 32 (Fig. 2) to come intocontact with@l sur-face such as di just before the stylus is brought outof engagement with the record as the pickup arm is being elevated. Whenthe cam wheel i8 begins to rotate to elevate the pickup arm out ofengagement with a record on the turntable, the roller 23 is in thenotchtZ. The rotation of the cam wheel i3 moves portion 2m of the camsurface 2i under the roller 23. 'I'he raising of the roller 23 andtherewith the lever 24 moves the adjustable screw 226 which raises therod 2'. rfhe raising oi the rod 2l moves upwardly the pla-te 32 which isfixed to the plate tu. When the lever 32 is moved by the upward movementof the pin 27, the plate Bil is moved upwardly and therewith the hollowshaft 28. As the lever 32 moves upwardly the adjustable screw tu engagesthe surface il and the pickup arm iii is elevated by pivotal movementabout the axis of the pin 33 to lift the stylus out of ensagement withthe record.

In. order to swing the pickup arm outwardly in a horizontal plane, thecam wheel it is pron vided with a cam surface d5, which is adapted toengage a pin 36. The pin (l is amxed to one end of a plate all which isp ivoted as at i8 to the base plate i@ (Fig. 2). The plate il isprovided with an aperture i9 (Figs. Zr-) through which pins 5i and 52extend. These pins Ei and yt2 are ailixed near one end of a lever theother end of which is Xed to the` shaft 2S to move therewith. Theoutward movement oi the pickup arm begins when cam portion 65A (Fig. 3)of the cam surface d5 moves into engagement with the pin (ifi. Thismoves the plate di' c in a clockwise direction (Figs. 4-6). When thestylus of the pickup arm is ln the tripping groove of a record on theturntable, the pins 5i and 52 arein the position shown in Fig. 5. Theclockwise movement of the plate il (Fig. 5) engages the left side of theaperture i9 with the pin iii to move the pin il and the lever il@attached thereto in a counterclockwise direction (Fig. 5). It is to benoted that any movement o the lever 53 while the pickup arm is out ofengagement with a record on the turntable is against friction created bythe engagement. of thelever Si? with the base of the pedestal it as atSti (Fig. l). The frictional engagement between the lever and thepedestal i6 occurs when the shaft 28, to which the lever lit is alxed,is raised, as has been previously described. The raising of the shaft 28brings the upper surface of the annular end of the lever 53 intofrictional engagement with the bottom surface of the pedestal Theclockwise movement of the plate il is against the biasing action oi aspring 5l which has one end anchored to the plate il and the other endanchored'tc a pin depending from the underside ci"y the base plate it)(ilg. l 'when the pins El and 5i? and the plate il have reached theposition shown in Fig. 6, the pickup arm iti hm been swung to itsoutwardmost position.

As the cam wheel i8 continues to rotate the cam portion 45B mig. 3) ofthe cam surface E TiOVEment.

moves into engagement with the pin GG. The tension of the spring 5l,which is sucient to overcome the frictional resistance of the lever S3created by its engagement with the base of the pedestal it) (Fig. 1)thereupon starts to swing the plate il ina counrclockwise direction(Fig. 6) causing the righthand side of the aperture fl@ to engage thepin E2 (Fig. 6) and moves the pin 52 and therewith the arm in aclockwise direction (Fig. 6) During this latter movement of the plate l?and the arm EES, the pickup arm -is swung inwardly. When the cam wheelit and the pin iii are in the position. shown in Fig. 3, where the piniii engages the at portion (25C, of the cam surface dii, the plate is inthe position shown in Fig. c and the pickup arm i5 is approximately overthe outer groove of a record on the turntable.

It is to be noted that the inward movement of the pickup arm i5 isslower than its outward This allows for the more accurate positioning ofthe pickup arm over the outer groove of a record on the turntable. Theslower inward movement of the pickup arm is achieved by the shape of thecam lit which includes the steep portion A which acts during the outwardmovement of the pickup arm and the gradual portion @35B which actsduring the inward movement of the pickup arm. The speed of the inwardand outward movement of the pickup arm is also due to the action ci theplate Gl on the pins 5iy and 52 at diierent times. When the pickup varmis being swung outwardly. the left .side of the aperture (i9 oi theplate il (Fig. 5) acts on the pin 5|. However, when the pickup arm isbeing swung inwardly, the right side of the aperture i9 of the plat/e diis acting on the lpin 52 (Fig. 6). Since pin 52 is further from :the

axis of rotation of lever 53 than pin 5i, it is obn vious that pin 52moves slower than pin 5i around the anis of rotation of the lever Whenthe pickup arm iti is in a position approximately over the outer grooveof a record on the turntable the pins 5i and ci? and lever 523 are in:the position shown in Fig. Il. Thereupon, the portion MB of the camsurface 2l moves under the roller 23. As the cam wheel it continues torotate, the notch @E gradually comes into engagement with the rollerwhich allows the lever 2li and the rod :lll to lower the pickup arm andtherewith the stylus into engagement with the outer groove of a recordon the turntable. With the lowering` oi the pickup arm, the lever 53 isIbrought out of frictional engagement with the pedestal it.

.tact that the outer grooves of disc ct at exactly the same distancefrom their outer edges, the stylus does not always drop exactly into theouter groove of a record. Means are provided for moving the stylus intothe outer groove of a record when fthe record is not provided with afeed-in groove. This means includes a tension spring 62 which isprovided on the plate as shown in Fiss. d-i

When the pickup arm iii is swung inwardly by movement of the plate di'(Figs, i and 6) ls. previously described, the pin E2 engages and forcesthe spring 62 outwardly thereby creating a tension on this spring. Thetension created is not sumcient to overcome the frictional resistance ofthe lever @S3 created by its movement against the base of the IpedestalI, but it is sumcient to swing the lever 53 when it is free oi' thepedestal When the pickup arm l5 is swung inwardly by the plate 41, andis lowered into engagement with the record, as heretofore described, andthe stylus has not engaged the outer upon moves the lever 53 andtherewith the pickup v armr I inwardly sufliciently far to move thestylus of the reproducerinto engagement with the outer groove of therecord.

Means are provided for limiting the inward movement of .fthe pickup armI5 so that the stylus may be positioned over the outer margin of atwelve-inch record. This means includes a lever 1U which is pivotallysupported by a bracket 1I depending from the underside of the base plateI3, (Figs. 2 and '7). Disposed intermediate the ends of the lever 'I0 isa depending ear 12 which is held out of the path of movement of a lug 13provided on the plate 41, by means of a flat spring 15 depending fromthe base plate I0 and engaging the fre'e end of the lever 10, as shownin Fig. '7.

Near its free end, the lever 10 is provided with a.

finger 16 which extends upwardly through an aperture 11 provided in thebase plate I0 (Fig. '1) and extends above the turntable II a suitabledistance as indicated in Fig. '1. The location of the finger 18 inrelation to the turntable, is such, as to lie in the path of a.twelve-inch record, when said record is moved into playing position uponthe turntable II. The mechanism shown and fully described in ourcopendlng application may be used for moving a record into playingposition upon the turntable il.

When a ten-inch record is placed upon the turntable, the periphery ofthe ten-inch record will not engage the finger 16 |to release the leverI 10. Thus, the plate 41 will` swing into its normal position to movethe pickup arm over the outer groove of a ten-inch record, as previouslydescribed. When a twelve-inch record is placed into playing positionupon the lturntable, the periphery of the twelve-inch record engages thefinger 16 (Figs. 2 and 7), and moves the finger 16 and therewith thelever 10 downwardly out of engagement with the spring catch 15. Thelever 10 is released by the spring 15 after the plate 41 has moved thepickup arm I5 to its outermost position as heretofore described. Whenthe plate 41 acts to swing the pickup arm I5 inwardly as previouslydescribed, the lug 13 engages the ear 12, which was released while thetwelve-inch record was placed upon the turntable. The engagement of thelug 13 with the ear 12 takes place when the pickup arm I5 has been|moved inwardly sufficiently iar to position the stylus over the outergroove of the twelveinch record. The engagement of (the elements 12 and13 takes place before -the nat portion 45C of the cam surface 45 engagesthe pin 411. H owever, continued movement of the cam wheel I8 acts tolower the stylus I4 into engagement with the outer groove of thetwelve-inch record.

When the twelve-inch record is played and the tripping mechanism,previously mentioned, is actuated, the shaft I3 and therewith the camAwheel i8 and a large cam wheel 30 affixed to the shaft i9 are rotated.vAs the cam wheel 80 continues to rotate, aucam 3| engages a pivotedlever 82 (Figs. 2 and 7) and lifts the lever 82 in a vertical plane. Thelever 82 iS pivotally Supported by a bracket B4 depending from thebottom of the base plate I0 (Fig. 2), and is arranged to engage thelower edge of the lever I0 (Fig. 7). Thus, ,as the lever 82 is raised,it engages and lifts the lever 10 to its normal position in engagement wth the spring 15, as shown in Fig. 7. When Va new recordv is moved intoplaying positionvupon the turntable (if it is a ten-inch record), themechanism will remain in its normal position to play the ten-inchrecord. However, if the new record is a twelve-inch record, themechanism will again be set automatically to position the pickup armover the beginning of the twelve-inch record as heretofore described.

Mode of operation The general mode of operation Vwill now be described..In this mode of operation it will be assumed that the pickup arm I5 hasbeen positioned to place the stylus I4 in the initial playing groove ofa record on the turntable II, as shown in Fig. 1. vmechanism (not shown)and the record is played, the pickup arm I5 moves inwardly toward thecenter of the record, as the stylus I4 follows the playing groove of therecord. As the pickup arm I5 moves inwardly, the lever '53.is likewisemoved inwardly by means of the tubular shaft 28, from the position shownin Fig. 4, to the position shown in Fig. 5.

After the record on the turntable Il is reproduced and the stylus I4 ofthe pickup arm I5 moves into the tripping groove of' the record, atripping mechanism (not shown) is initiated to start the rotation of theshaft I3. The rotation of the cam wheels I8 and 8U with the shaft I9 isso timed that the ilrst operation which occurs.

after the shaft I9 begins to rotate, is to lift the stylus I4 of thepickup arm I5 out of engagement to raise the lever 24 and the adjustablescrew 26' from the position shown in Fig. 2. This movement of the lever24 raises the rod 21 vertically within the tubular shaft 28 (Fig. l). Asthe rod 21 moves upwardly the upper end of the rod engages the plate 32and pivots the plate 32` in Ya clockwise direction (Fig. l) on the pivotpin 33.

The plate 32 in moving in a clockwise direction, moves the screw 40 intoengagement with the surface 4I. Thereafter the continued upward movementof the pin 21 raises the .pickup arm I5 and therewith the stylus I4 outof engagement with the record on the turntable I I.

After the pickup arm I5 is raised, the cam portion 45A of the cam wheelI8 (Figs. 2 and 3) engages the pin 46 and moves it, and therewith the Asthe turntable Il is rotated by a f plate 41 in a clockwise directionagainst the biasing actionl of the spring 51 from the position shown inFig. 5. plate 41 moves the left-hand side ofthe aperture 49, oiA theplate 41, into engagement with the pin 5I to move the pin 5I andtherewith the lever 53 in a counterclockwise direction. 'I'hecounterclockwise movement of the lever53 also moves the tubular shaft 28and the pickup arm I5 in acorresponding direction until the pickup armI5 is table II, in the manner fully described in oury copendingapplication, the cam portion 45B (Fig.

3) engages the pin 48.A As the cam wheel I8 con- The clockwise movementof the in its outwardmost position. When the pickupy i tinues .torotate, thetension of the spring 51. I

starts to swing the plate 41 in a'counterclockwise j direction from theposition shown in Fig. 6. The

2,387,916 v M and adapted to engage said rst member for mov 6 ment withthe record.

ing the stylus of said pickup arm into the outer groove of a record onsaid' turntable after the stylus of said pickup arm is brought `intoengage- L. KNOX. FRITZ KAHL.

